Under ʿAbd al-Malik (reigned 685–705) the Umayyad caliphate continued to expand. Muslim armies invaded Mukrān and Sindh in India, while in Central Asia the Khorāsānian garrisons conquered Bukhara, Samarkand, Khwārezm, Fergana, and Tashkent. In an extensive program of Arabization, Arabic became the official state language; the financial administration of the empire was reorganized, with Arabs replacing Persian and Greek officials; and a new Arabic coinage replaced the former imitations of Byzantine and Sasanian coins. Communications improved with the introduction of a regular post service from Damascus to the provincial capitals, and architecture flourished (Source: Britanica).
Ummayyads in Persia: Abdul Malik I and His Economic Initiatives
